libmount: Add support for FSCONFIG_CMD_CREATE_EXCL

* Add API functions mnt_context_enable_exclusive() and mnt_context_is_exclusive()

* Use the new flag when creating the superblock

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libmount/docs/libmount-sections.txt b/libmount/docs/libmount-sections.txt
index bb43f71f2ec801ac9d16739cc23e51e87142f5dc..60dffba7e184f851059bd496ad9981c87bb69bd8 100644 (file)
--- a/libmount/docs/libmount-sections.txt
+++ b/libmount/docs/libmount-sections.txt
@@ -31,6 +31,7 @@ mnt_context_disable_canonicalize
 mnt_context_disable_helpers
 mnt_context_disable_mtab
 mnt_context_disable_swapmatch
+mnt_context_enable_exclusive
 mnt_context_enable_fake
 mnt_context_enable_force
 mnt_context_enable_fork
@@ -71,6 +72,7 @@ mnt_context_helper_executed
 mnt_context_helper_setopt
 mnt_context_init_helper
 mnt_context_is_child
+mnt_context_is_exclusive
 mnt_context_is_fake
 mnt_context_is_force
 mnt_context_is_fork

diff --git a/libmount/src/context.c b/libmount/src/context.c
index 55cf75ddd150353e146ef17562f74afacbea9f11..122d2dbf2375915b431e38f2a38233a4388e3c01 100644 (file)
--- a/libmount/src/context.c
+++ b/libmount/src/context.c
@@ -572,7 +572,7 @@ int mnt_context_is_lazy(struct libmnt_context *cxt)
  * @cxt: mount context
  * @enable: TRUE or FALSE
  *
- * Enable/disable only-once mount (check if FS is not already mounted).
+ * Enable/disable only-once mount (check if source + target is not already mounted).
  *
  * Returns: 0 on success, negative number in case of error.
  */
@@ -592,6 +592,31 @@ int mnt_context_is_onlyonce(struct libmnt_context *cxt)
        return cxt->flags & MNT_FL_ONLYONCE ? 1 : 0;
 }
 
+/**
+ * mnt_context_enable_exclusive
+ * @cxt: mount context
+ * @enable: TRUE or FALSE
+ *
+ * Enable/disable exclusive mount (only one FS instance is allowed).
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_enable_exclusive(struct libmnt_context *cxt, int enable)
+{
+       return set_flag(cxt, MNT_FL_EXCL, enable);
+}
+
+/**
+ * mnt_context_is_exclusive:
+ * @cxt: mount context
+ *
+ * Returns: 1 if exclisive mount is enabled or 0
+ */
+int mnt_context_is_exclusive(struct libmnt_context *cxt)
+{
+       return cxt->flags & MNT_FL_EXCL ? 1 : 0;
+}
+
 /**
  * mnt_context_enable_fork:
  * @cxt: mount context

diff --git a/libmount/src/hook_mount.c b/libmount/src/hook_mount.c
index 35f3a8d749ce7a1a50f52c210e8f5aee70b6ecf2..b545d2441f51d08cf56c317251676b312a5251c1 100644 (file)
--- a/libmount/src/hook_mount.c
+++ b/libmount/src/hook_mount.c
@@ -216,6 +216,26 @@ done:
        return rc != 0 && errno ? -errno : rc;
 }
 
+static int create_superblock(struct libmnt_context *cxt,
+               const struct libmnt_hookset *hs, int fd)
+{
+       int rc = 0;
+
+       DBG(HOOK, ul_debugobj(hs, " create FS %s",
+                       mnt_context_is_exclusive(cxt) ? "excl" : ""));
+       errno = 0;
+
+       if (mnt_context_is_exclusive(cxt))
+               rc = fsconfig(fd, FSCONFIG_CMD_CREATE_EXCL, NULL, NULL, 0);
+       else
+               rc = fsconfig(fd, FSCONFIG_CMD_CREATE, NULL, NULL, 0);
+
+       hookset_set_syscall_status(cxt, "fsconfig", rc == 0);
+
+       DBG(HOOK, ul_debugobj(hs, " create done [rc=%d]", rc));
+       return rc != 0 && errno ? -errno : rc;;
+}
+
 static int open_fs_configuration_context(struct libmnt_context *cxt,
                                         struct libmnt_sysapi *api,
                                         const char *type)
@@ -272,11 +292,8 @@ static int hook_create_mount(struct libmnt_context *cxt,
 
        if (!rc)
                rc = configure_superblock(cxt, hs, api->fd_fs, 0);
-       if (!rc) {
-               DBG(HOOK, ul_debugobj(hs, "create FS"));
-               rc = fsconfig(api->fd_fs, FSCONFIG_CMD_CREATE, NULL, NULL, 0);
-               hookset_set_syscall_status(cxt, "fsconfig", rc == 0);
-       }
+       if (!rc)
+               rc = create_superblock(cxt, hs, api->fd_fs);
 
        if (!rc) {
                int fd = fsmount(api->fd_fs, FSMOUNT_CLOEXEC, 0);

diff --git a/libmount/src/libmount.h.in b/libmount/src/libmount.h.in
index 9d173ff0e4f201ac2f7d77e635d8e4dd22a3a4c8..f30f94cdc5c6fbc4b0abf6181f2bc513a155b5a6 100644 (file)
--- a/libmount/src/libmount.h.in
+++ b/libmount/src/libmount.h.in
@@ -803,6 +803,7 @@ extern int mnt_context_helper_setopt(struct libmnt_context *cxt, int c, char *ar
 extern int mnt_context_set_optsmode(struct libmnt_context *cxt, int mode);
 extern int mnt_context_disable_canonicalize(struct libmnt_context *cxt, int disable);
 extern int mnt_context_enable_onlyonce(struct libmnt_context *cxt, int enable);
+extern int mnt_context_enable_exclusive(struct libmnt_context *cxt, int enable);
 extern int mnt_context_enable_lazy(struct libmnt_context *cxt, int enable);
 extern int mnt_context_enable_rdonly_umount(struct libmnt_context *cxt, int enable);
 extern int mnt_context_enable_rwonly_mount(struct libmnt_context *cxt, int enable);
@@ -820,6 +821,8 @@ extern int mnt_context_get_optsmode(struct libmnt_context *cxt);
 
 extern int mnt_context_is_onlyonce(struct libmnt_context *cxt)
                        __ul_attribute__((nonnull));
+extern int mnt_context_is_exclusive(struct libmnt_context *cxt)
+                       __ul_attribute__((nonnull));
 extern int mnt_context_is_lazy(struct libmnt_context *cxt)
                        __ul_attribute__((nonnull));
 extern int mnt_context_is_rdonly_umount(struct libmnt_context *cxt)

diff --git a/libmount/src/libmount.sym b/libmount/src/libmount.sym
index 284869a3577acdf26170b95e90cc28d4742ef563..cbef26fb0b1e061362ca4b8b3e9a375127b88840 100644 (file)
--- a/libmount/src/libmount.sym
+++ b/libmount/src/libmount.sym
@@ -408,3 +408,8 @@ MOUNT_2_41 {
        mnt_table_refer_statmnt;
        mnt_unref_statmnt;
 } MOUNT_2_40;
+
+MOUNT_2_42 {
+       mnt_context_enable_exclusive;
+       mnt_context_is_exclusive;
+} MOUNT_2_41;

diff --git a/libmount/src/mountP.h b/libmount/src/mountP.h
index f4d80c5dfc0887c368c345b734193aceeb6760e5..7c504f95ce68176d1d05cd43e8423e1ad00e585e 100644 (file)
--- a/libmount/src/mountP.h
+++ b/libmount/src/mountP.h
@@ -516,6 +516,7 @@ struct libmnt_context
 #define MNT_FL_NOSWAPMATCH     (1 << 13)
 #define MNT_FL_RWONLY_MOUNT    (1 << 14)       /* explicit mount -w; never try read-only  */
 #define MNT_FL_ONLYONCE                (1 << 15)
+#define MNT_FL_EXCL            (1 << 16)
 
 #define MNT_FL_MOUNTDATA       (1 << 20)
 #define MNT_FL_TAB_APPLIED     (1 << 21)       /* fstab merged to cxt->fs */